GREENVILLE, S.C. — Shortly before 11 p.m. on Friday, without a hint of ceremony, it happened: Greenville, this charming little city on the banks of the Reedy River, became the epicenter of Duke hatred.

The Blue Devils don’t always need help in this department, of course. During this year’s NCAA tournament, they are the East Region’s No. 2 seed and a trendy pick to reach yet another Final Four. They are the bluest of basketball’s blue bloods at an elite private university. They have a couple proper villains in Coach Mike Krzyzewski and guard Grayson Allen.

But here, now, the Blue Devils are almost surrounded. Two of the three remaining non-Duke teams at Bon Secours Wellness Arena — North Carolina, the top seed in the South Region, and South Carolina, the No. 7 seed in the East and Duke’s next opponent — have fan bases with reason to dislike Duke, and on Sunday they’ll all pile into the building together for the second-round games.

North Carolina is here and so is its well-traveled and full-throated cluster of fans. Duke University, for the uninitiated, is 10 miles from the University of North Carolina’s campus, and the teams have been squaring off — often at college basketball’s highest level — since 1920. They’ve faced off in almost every imaginable scenario, the Tar Heels with a 25-win series advantage, but they have somehow never run into each other in the NCAA tournament.

This is the tournament that could change, though it’d be a showdown with the longest road and the highest possible stakes: the two old rivals, their stately coaches and their passionate fans making it to the national championship game. Even on opening weekend, weeks before the title game, that appetizing possibility was on the menu.

“It will be awesome,” Tar Heels swingman Theo Pinson said Thursday, before either team had even played a tournament game. “That means we’re in the national championship, first of all. I mean, it’s a long way to go. I can’t even think about Duke right now. Right now, honestly, I’m going to focus on tomorrow. But that would be one game that everybody will be watching.”

(Rainier Ehrhardt/Associated Press)

On Friday, as Duke made easy work out of 15th-seeded Troy, South Carolina fans practiced their catcalls — especially when Allen touched the ball, when he shot free throws, when Allen’s feet became tangled in the first half and his body smacked onto the hardwood.

Allen is as fundamentally sound and clutch as he is skilled at finding new ways to trip or kick opponents, maybe the finest Duke villain since J.J. Redick. Krzyzewski suspended Allen for a game earlier this season, controversy has seemed to follow the junior guard from arena to arena, Allen kept pushing the limits and alternating between enraging opposing fans and averaging 14.1 points to help break their hearts.

He is, in other words, so very Duke.

“My job is to give energy,” Allen told reporters after his team’s 87-65 first-round win against Troy, and the player is as good at energizing his teammates as he is at inciting other teams’ fans.

When he jogged onto the floor a few minutes after the game began, the arena welcomed him with the loudest boos of the day. The man, like his coach — Krzyzewski rarely walks onto the floor before games alongside his follow coaches, preferring to enter a little later and alone — likes to make an entrance.

South Carolina, by the way, helped create Duke basketball. It’s a dusty, old piece of trivia among fans with a well-earned inferiority complex — the Gamecocks’ first-round victory against Marquette was their first NCAA tournament win in 44 years — but it’s nevertheless a deep-seated reason South Carolina fans will be ready for Sunday’s contest.

The Gamecocks, who participated in the ACC alongside Duke until 1971, had some bad luck (and were the victims of poor long-term planning) a few years after that. After the 1979-80 season, South Carolina’s administration grew tired of playing in the National Invitation Tournament and forced Frank McGuire, their Hall of Fame coach, into retirement. The school’s search for a replacement landed on Duke Coach Bill Foster, who had been a solid leader in Durham; just before he made the move to Columbia, he had led the Blue Devils to the ACC tournament championship.

Anyway, when Foster left, Duke administrators were listless. They had to find a replacement, and eventually they looked deep into college basketball’s ranks to find Army’s 33-year-old coach, an unproven but disciplined man named Mike Krzyzewski.

The short version of what came next is that Krzyzewski, of course, reinvented Duke basketball and has become one of the finest coaches in basketball history; now 70, “Coach K” has won five national titles and reached a dozen Final Fours. South Carolina, by the way, has reached the NCAA tournament since 1980 the same number of times Duke has cut down the nets as national champs. Foster lasted six seasons and never reached the NCAA tournament.

So there’s some resentment. Which, in the absence of sustained joy in most South Carolina sports, has become a go-to emotion in Columbia.

Then again, Sunday will offer a chance at some measure of redemption, though fulfilling that would require a massive upset (albeit on an arena floor that, because of political disputes in North Carolina, is actually closer to South Carolina’s campus than either of the higher-seeded programs from Tobacco Road).

“We need to be real good to be able to compete with a team like Duke in a couple of days,” Gamecocks Coach Frank Martin said late Friday, shortly before midnight. By then, the Blue Devils were already preparing for Sunday, when that evening — just after UNC finishes its game against Arkansas — Duke players and coaches will stride onto the floor as a collection of villains these parts have scarcely ever seen.

Kent Babb is a sports features writer for The Washington Post, focusing on the NFL, college sports, the NBA, and the intersections of sports with social, cultural and political issues. He joined The Post in 2012.